1. Field of the Invention
The present invention relates in general for a passive entry vehicle transmitter/receiver device, and more particularly, to a passive entry vehicle transmitter/receiver integrated within a personal portable device.
2. Description of the Related Art
Remote keyless entry (RKE) systems are well known in the automotive industry for remotely accessing vehicles without the use of a key. RKE systems may be characterized as active or passive. In an active entry system, a user must activate a switch or pushbutton on a remote transmitter in order to have a desired remote function performed, such as locking or unlocking the vehicle doors or de-latching the trunk. In contrast, a passive entry system does not require a pushbutton by a user in order to have a desired remote function performed.
In passive systems, a remote receiver and transmitter (or transceiver) is carried with the user. Such a device is often referred to as a “FOB” or a “card”. The FOB is commonly carried on a key chain of the user. The FOB when prompted transmits a radio frequency (RF) signal to the a module within the vehicle for performing a variety of remote vehicle function such door lock/unlock, enabling engine start, or activating external/internal lighting. Passive entry systems include a transmitter and receiver (or transceiver) in an electronic control module disposed within the vehicle. The transceiver is in communication with one or more devices (e.g., door lock mechanism) for determining when a request for actuation of a device is initiated (e.g., lifting a door handle) by a user.
Upon sensing the actuation, the transceiver broadcasts a passive entry interrogating signal. The fob upon receiving the interrogating signal determines if the interrogating signal is valid. If it is determined a valid signal, then the fob automatically broadcasts an output signal which includes an encrypted or rolling identification code to the electronic control module. The electronic module thereafter determines the validity of the output signal and generates a signal to the device to perform an operation (e.g., the door lock mechanism to unlock the door) if the output signal is determined valid.
In performing the passive entry function, the device must be carried on the user and within a broadcasting region of the interrogation signal to allow operation of the automated feature (i.e., door unlock). It is desirable to have a device that is easily portable and commonly carried with the person at all times. As stated earlier, the fob is commonly attached to a key chain. The key chain typically includes a plurality of keys for accessing a variety of items such as the user's house, office, desks, relatives house, safety devices and the like, and the addition of the fob makes for an additional bulky item on an already overloaded key chain. In addition, the ever increasing store discount membership cards which are attachable to the key chain adds to the overloaded and bulky key chain.
Furthermore, if a user owns more than one vehicle, then multiple fobs are utilized for accessing each vehicle. If the user desires to have all vehicle keys on one key chain, then each fob is added on the single key chain which creates an over-capacitized, bulky, and awkward item to carry especially in a users pocket. Alternatively, if multiple users utilize a single vehicle, it is convenient for each user to have a set of keys to the vehicle. However, if multiple key rings are used for a single vehicle, then multiple fobs must be provided on each key chain, or a respective user would have to remember to retrieve the single fob whenever the vehicle needs to be accessed.